As far as I can see, Jeanna, Cooke & Lewis doors are around 19mm thick - standard for modern kitchen doors.
It rather depends on the age of your B&Q units. Many years ago units were made from around 15-16mm thick board. Some problems may come up where a door may not open fully in certain circumstances.
This can often be overcome by packing off the hinge mounts to bring them away from the carcass.
New doors usually come with standard 32mm cut-outs for the hinges...... also in standard positions. Go with this, but simply re-position the hinge mounts to line up.
In theory, it's all possible. There's no way anyone can be certain without being there and trying things out. You'd need a good knowledge of kitchen fitting to overcome any problems though.
If it were me, I would certainly go for it... and adjust/reposition as necessary. You may well need to get someone in.